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arXiv · 2404.18073

Charge and spin density wave orders in field-biased Bernal bilayer graphene

Zhiyu Dong·Patrick A. Lee·Leonid Levitov
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Abstract

This paper aims to clarify the nature of a surprising ordered phase recently reported in biased Bernal bilayer graphene that occurs at the phase boundary between the isospin-polarized and unpolarized phases. Strong nonlinearity of transport at abnormally small currents, with $dI/dV$ vs. $I$ sharply rising and then falling back, is typical for a charge/spin-density-wave state (CDW or SDW) sliding transport. Here, however, it is observed at an isospin-order phase boundary, prompting a question about the CDW/SDW mechanism and its relation to the quantum critical point. We argue that the observed phase diagram cannot be understood within a standard weak-coupling picture. Rather, it points to a mechanism that relies on an effective interaction enhancement at a quantum critical point. We develop a detailed strong-coupling framework accounting for the soft collective modes that explain these observations.

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Zhiyu Dong, Patrick A. Lee, Leonid Levitov. 2024-04-28. Charge and spin density wave orders in field-biased Bernal bilayer graphene. https://arxiv.org/abs/2404.18073

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